HID: hidraw: fix nonblock read return EAGAIN after device removed

When nonblock read the condition check (file->f_flags & O_NONBLOCK) always be
true, signal_pending and device exist checking never get a chance to run, so
the user mode code always get EAGAIN even if device removed. move nonblock mode
checking to the last can fix this problem.

Signed-off-by: Founder Fang <founder.fang@gmail.com>
Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

1 files changed, 4 insertions, 4 deletions

diff --git a/drivers/hid/hidraw.c b/drivers/hid/hidraw.c
index 7c47fc3f7b2b..1d8c0219117e 100644
--- a/drivers/hid/hidraw.c
+++ b/drivers/hid/hidraw.c
@@ -57,10 +57,6 @@ static ssize_t hidraw_read(struct file *file, char __user *buffer, size_t count,
                         set_current_state(TASK_INTERRUPTIBLE);
 
                         while (list->head == list->tail) {
-                                if (file->f_flags & O_NONBLOCK) {
-                                        ret = -EAGAIN;
-                                        break;
-                                }
                                 if (signal_pending(current)) {
                                         ret = -ERESTARTSYS;
                                         break;
@@ -69,6 +65,10 @@ static ssize_t hidraw_read(struct file *file, char __user *buffer, size_t count,
                                         ret = -EIO;
                                         break;
                                 }
+                                if (file->f_flags & O_NONBLOCK) {
+                                        ret = -EAGAIN;
+                                        break;
+                                }
 
                                 /* allow O_NONBLOCK to work well from other threads */
                                 mutex_unlock(&list->read_mutex);